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(No Model.) 2 Sheets-Sheet 1.

T. H. ORAIG. DIFFERENTIAL SPUR GEAR HOIST.

No. 554,658. Patented Feb. 18, 1896.

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2 I A R O DIFFERENTIAL SPUR GEAR HOIST.

No. 554,658. Patented Feb. 18, 1896.

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NITED STATES .ATENT OFFICE.

THOMAS HANNIFORD CRAIG, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE-HALF TO WILLIAM B. MOSKIMMON, OF SAME PLACE.

DIFFERENTIAL SPU R-G EAR HOIST.

SPECIFICATION forming part of Letters Patent No. 554,658, dated February 18, 1896.

Application filed February 11, 1895. Serial No. 537,976. (No model.)

To all whom it may concern:

Be it known that I, THOMAS HANNIFORD CRAIG, a citizen of the United States, residin g at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Differential Spur-Gear Hoists; and I do hereby declare the following to be a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same.

The invention relates to differential spurgear hoists.

The object is to produce a perfectly-balanced device of this class and thereby secure an equal distribution of strain upon the members or parts forming the frame; further, to employ an extremely simple and inexpensive construction, possessing advantages. in point of simplicity, durability and general efficiency.

WVith these objects in view the invention consists in various novel combinations and arrangements of parts to be described and claimed.

In the accompanying drawings, forming part of this specification, in which similar letters of reference indicate corresponding parts in the several views, Figure 1 is a view in elevation of one embodiment of the invention. Fig. 2 is a View in central vertical section of the same. Fig. 3 is a View in detail of the shaft and the gear integral therewith.

In the drawings, A represents a hanger, which comprises a cross-bar at, having an upward-proj ectin g hook a integral therewith or suitably fixed thereto, and is socketed at a to receive threaded bolts a upon which duplicate depending arms a a are supported, and terminate at their lower ends in apertured heads a in which a shaft is mounted upon roller-bearin gs a Revolving upon the roller-bearings with and secured to the inner face of the head of one of these arms is a gear a B represents the shaft above referred to, and forming part of this shaft is a gear 6, the function of which will appear later on. Keyed upon the outer ends and revolving with the shaft are two grooved chain-pulleys b 19 the grooved peripheries thereof being toothed 'or pocketed to receive and grip the chains,which latter are attached to a cross-bar provided with an engaging-hook, from which the artifrom the operating-wheel is transmitted through one or more intermeshing pinions 0 common to both gears, the pinion or pinions being rotatably carried in bracketed bearings 0 upon the web of the wheel.

In the present embodiment of the invention the fixed gear has twenty-six teeth, the loose gear twenty-seven, and the pinion ten. Upon rotating the operating-wheel through one complete revolution the pinion lying in engagement with both gears causes the loose gear to move one twenty-sixth of that distance. Therefore, to rotate the loose gear through a complete revolution, the operatingwheel carrying the pinion must be given twenty-six turns, the article to be hoisted being held suspended at any height by the pinion becoming locked in the fixed gear against independent rotation.

Having thus fully described my invention, what I claim is -In a balance-hoist, the combination with a hanger having substantially duplicated arms, of a horizontal shaft supported by the hanger, roller-bearings between the shaft and hanger, an operating-wheel supported on the shaft and adapted to revolve independent of the shaft, roller-bearings between the shaft and operating-wheel, a fixed gear-wheel supported on the shaft and axially disposed in relation thereto, roller-bearings between the fixed gear-wheel and shaft, a gear-wheel keyed on the shaft, a pinion journaled on the actuatingwheel meshing with the fixed gear-wheel, and gear-wheel carried by the shaft and chaincarrying wheels keyed to the shaft on opposite sides of the actuating-wheel, substantially as described.

In testimony whereof I have hereunto affixed my signature in the presence of two subscribing witnesses.

THOMAS HANNIFORD CRAIG.

Witnesses:

NORMAN H. STEVENS, Enw. H. BARRAS.

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